Keywords are important because they are the linchpin between what people are searching for and the content you are providing to fill that need. Your goal in ranking on search engines is to drive organic traffic to your site from the search engine result pages (SERPs), and the keywords you choose to target (meaning, among other things, the ones you choose to include in your content) will determine what kind of traffic you get. If you own a golf shop, for example, you might want to rank for "new clubs" — but if you're not careful, you might end up attracting traffic that's interested in finding a new place to dance after dark.
QUOTE: “In place of a pop-up try a full-screen inline ad. It offers the same amount of screen real estate as pop-ups without covering up any content. Fixing the problem depends on the issue you have for example if it’s a pop-up you’ll need to remove all the pop-up ads from your site but if the issue is high ad density on a page you’ll need to reduce the number of ads” Google, 2017

QUOTE: “They follow the forms you gather data you do so and so and so forth but they don’t get any laws they don’t haven’t found out anything they haven’t got anywhere yet maybe someday they will but it’s not very well developed but what happens is an even more mundane level we get experts on everything that sound like this sort of scientific expert they they’re not scientist is a typewriter and they make up something.”  Richard Feynman, Physicist
The reality in 2019 is that if Google classifies your duplicate content as THIN content, or MANIPULATIVE BOILER-PLATE or NEAR DUPLICATE ‘SPUN’ content, then you probably DO have a severe problem that violates Google’s website performance recommendations and this ‘violation’ will need ‘cleaned’ up – if – of course – you intend to rank high in Google.
A Coursera Specialization is a series of courses that helps you master a skill. To begin, enroll in the Specialization directly, or review its courses and choose the one you'd like to start with. When you subscribe to a course that is part of a Specialization, you’re automatically subscribed to the full Specialization. It’s okay to complete just one course — you can pause your learning or end your subscription at any time. Visit your learner dashboard to track your course enrollments and your progress.
You likely have a few keywords in mind that you would like to rank for. These will be things like your products, services, or other topics your website addresses, and they are great seed keywords for your research, so start there! You can enter those keywords into a keyword research tool to discover average monthly search volume and similar keywords. We’ll get into search volume in greater depth in the next section, but during the discovery phase, it can help you determine which variations of your keywords are most popular amongst searchers.

This is why developing a list of keywords is one of the first and most important steps in any search engine optimization initiative. Keywords and SEO are directly connected when it comes to running a winning search marketing campaign. Because keywords are foundational for all your other SEO efforts, it's well worth the time and investment to ensure your SEO keywords are highly relevant to your audience and effectively organized for action.
It helps to improve your ranking for certain keywords. If we want this article to rank for the term ’SEO basics’ then we can begin linking to it from other posts using variations of similar anchor text. This tells Google that this post is relevant to people searching for ‘SEO basics’. Some experts recommend varying your anchor text pointing to the same page as Google may see multiple identical uses as ‘suspicious’.
Robots.txt is not an appropriate or effective way of blocking sensitive or confidential material. It only instructs well-behaved crawlers that the pages are not for them, but it does not prevent your server from delivering those pages to a browser that requests them. One reason is that search engines could still reference the URLs you block (showing just the URL, no title or snippet) if there happen to be links to those URLs somewhere on the Internet (like referrer logs). Also, non-compliant or rogue search engines that don't acknowledge the Robots Exclusion Standard could disobey the instructions of your robots.txt. Finally, a curious user could examine the directories or subdirectories in your robots.txt file and guess the URL of the content that you don't want seen.

There are a lot of definitions of SEO (spelled Search engine optimisation in the UK, Australia and New Zealand, or search engine optimization in the United States and Canada) but organic SEO in 2019 is still mostly about getting free traffic from Google, the most popular search engine in the world (and almost the only game in town in the UK in 2019):
SEM is a broader term than SEO, and is used to encompass different options available to use a search engine’s technology, including paid ads. SEM is often used to describe acts associated with researching, submitting and positioning a website within search engines.  It includes things such as search engine optimization, paid listings and other search-engine related services and functions that will increase exposure and traffic to your Web site. 
QUOTE: “Google Webmaster Tools notice of detected doorway pages on xxxxxxxx – Dear site owner or webmaster of xxxxxxxx, We’ve detected that some of your site’s pages may be using techniques that are outside Google’s Webmaster Guidelines. Specifically, your site may have what we consider to be doorway pages – groups of “cookie cutter” or low-quality pages. Such pages are often of low value to users and are often optimized for single words or phrases in order to channel users to a single location. We believe that doorway pages typically create a frustrating user experience, and we encourage you to correct or remove any pages that violate our quality guidelines. Once you’ve made these changes, please submit your site for reconsideration in Google’s search results. If you have any questions about how to resolve this issue, please see our Webmaster Help Forum for support.” Google Search Quality Team

QUOTE: “How do I move from one domain to another domain and try to preserve the rankings as best as possible?…do a 301 permanent redirect to the new location (assuming that you’re you’re moving for all time and eternity so this is the good case for a permanent or 301 redirect if you were planning to undo this later or it’s temporary then you’d use a 302 redirect)…. search engines should be able to follow the trail of all the 301 redirects” Matt Cutts, Google
QUOTE: “Returning a code other than 404 or 410 for a non-existent page (or redirecting users to another page, such as the homepage, instead of returning a 404) can be problematic. Firstly, it tells search engines that there’s a real page at that URL. As a result, that URL may be crawled and its content indexed. Because of the time Googlebot spends on non-existent pages, your unique URLs may not be discovered as quickly or visited as frequently and your site’s crawl coverage may be impacted (also, you probably don’t want your site to rank well for the search query” GOOGLE
When Googlebot crawls a page, it should see the page the same way an average user does15. For optimal rendering and indexing, always allow Googlebot access to the JavaScript, CSS, and image files used by your website. If your site's robots.txt file disallows crawling of these assets, it directly harms how well our algorithms render and index your content. This can result in suboptimal rankings.